The invention relates to a medical electrode for conducting signals (in particular, for conducting signals from the human skin), which is built up in at least two layers. A preferably metallic signal conductor which can be connected to the signal-emitting subject is arranged between an upper top layer and an adhesive layer which can be brought into contact with the signal-emitting subject. The electrode has a tapping pad, and a preferably electrically insulating covering element is arranged between the tapping pad and the signal-emitting subject.
Known electrodes which can be stuck on to the skin comprise an adhesive layer having an opening for accommodating an electrically conductive gel for contacting the signal-emitting subject, an upper top layer and a signal-conducting layer arranged in between, and have a tapping pad which is formed by the upper top layer and the signal-conducting layer. To prevent the signal-conducting layer, which is freely accessible from the under-side of the tapping pad, from coming into contact with the signal-emitting subject, as a result of which the signal conducted would be influenced, it is conventional to arrange on the side of the preferably electrically non-conducting adhesive layer facing the signal-emitting subject a skin-friendly plaster element which masks the tapping pad and thus prevent contact between the signal-conducting layer and the signal-emitting subject in the region of the tapping pad.
It is furthermore known from DE 197 30 811 C1 to provide the tapping pad with a non-adhesive covering on the side facing the signal-emitting object and to shield the signal-conducting layer of the electrode against external interferences in this manner.
It has been found, however, that the coverings, which as a rule are produced from plastic, for example from PVC, PE or PET, undergo static charging during the measuring operation, in particular if the signal-emitting subject moves, as is the case, for example, when carrying out an exercise ECG. This static charging of the covering element has an effect on the signal-conducting layer, with which the covering element is indeed in direct contact, and influences the conducted signal in this manner.
A further disadvantage of the known medical electrodes which have emerged is that the plastics which are used for producing the covering have static properties of varying favorability. Considered from this point of view, PVC is the most suitable for producing the covering. On the other hand, PE or PET are preferred for producing the upper top layer of the medical electrode, inter alia for ecological reasons. In the context of a simple and inexpensive production process, it would be appropriate to construct the upper top layer and the covering in one piece, which in practice leads to either an electrode having a high-quality upper top layer but poorer static properties for the covering, or an electrode having a high-quality covering but a less suitable upper top layer.